My daughter’s doll lost a hand. After searching for a few days, she suggested I make her doll a new hand. My kids apparently think their dad can create and fix anything. While I had never attempted to create a solid model of a toy part, I was ready for the challenge.
I began with some geometric primitive shapes in Tinkercad, a 3D-modeling application. For the palm of the hand, I started with a sphere and extended that with a rectangular prism. The post that extended outward from hand to attach it to the arm of the doll was created with a cylinder and a torus wrapped around it. This cylinder jutted outward from the sphere, and the torus would allow for the hand to snap into the doll’s arm - if only my precise measurements were correct. I used a caliper to measure the post and hand dimensions of the right hand and reversed it for my left-hand model.
After building the solid model of the doll’s left-hand, I tweaked it and made adjustments to the dimensions. Trying to make it look a little more life-like, I added some curves to the palm by using another sphere shape to cut away at the rectangular prism. When I had a decent enough model, I began printing the doll’s prosthetic hand on a 3D printer with PLA filament.
It looks all right, and it fit even better than I had expected. It worked well and my daughter appreciated it. We had a good talk too about people and animals with prosthetics. It was a learning experience for us both.
The physics behind the tippe top toy have been the subject of studies by scientists for years - dating back to the early 1890s. The tippe top is spun just like any other top, but pulls a surprise stunt. The top flips over and spins on its stem when given a strong twist. Why does the tippe top flip over? What does this mean for anyone planning to make one on a 3D printer? Nobel Prize winners, Wolfgang Pauli and Niels Bohr, take a break with a tippe top at the 1954 inauguration of the Institute of Physics in Lund, Sweden. Early Top Patents The first patent for the top, listed as “Wendekreisel”, was filed in Germany by Helene Sperl in 1891. While the patent seems to describe the top’s inversion property, reproductions of the top have proved unsuccessful. The patent expired after one year because the fee wasn’t paid. During a trip to South America, Danish engineer Werner Østberg noticed kids spinning a small, round fruit. While spinning, the fruit would flip over (or...
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